WASHINGTON -- The probe into the January crash of Alaska Airlines Flight 261, perhaps more than any other recent aviation accident, has revealed systemic and troubling deficiencies in the FAA's day-to-day supervision of airlines.

Testimony from four days of public hearings and documents released by crash investigators depicted an understaffed force of Federal Aviation Administration inspectors -- often suffering from poor morale and distracted by persistent staff turmoil -- that failed to detect or act on serious lapses by...